In order to coordinate the activities necessary for survival of a multicellular organism, the individual cells of the organism must communicate with each other via cell-surface receptors and their ligands. The known receptors are generally classified based on the particular method of signal transduction (translation of an extracellular signal into an intracellular signal) which is most characteristic of the receptor class. One class of receptors is the group of receptor protein-tyrosine kinases, which have intracellular kinase domains that are activated by binding of one or more ligands, resulting in autophosphorylation of specific tyrosine residues and activation of intracellular signalling molecules.
The largest subfamily of the receptor protein-tyrosine kinases (RPTK) is the Eph subfamily, characterized by the oncogene eph (Hirai et al., Science 238:1717-1720 (1987)). The ligands for the Eph RPTKs constitute a rapidly expanding group of molecules which are either transmembrane or glycosylphosphatidylinositol (GPI)-linked (Pandey et al., Current Biology 5(9) :986-989 (1995)). It is likely that the Eph receptor-ligand interactions play important roles in the growth, development and survival of multicellular organisms.
The invention pertains to a method of modulating LERK-2-mediated cell adhesion, comprising the step of contacting a cell expressing LERK-2 and/or a cell expressing a receptor for LERK-2 with an inhibitor or promoter of LERK-2-mediated cell adhesion. In a particular embodiment, the receptor for LERK-2 is selected from the group consisting of Nuk, Cek5, Tyro5 and ERK, and in a preferred embodiment the receptor for LERK-2 is Nuk. In one embodiment, the cell expressing a receptor for LERK-2 is a lymphoid cell, particularly a T cell.
In one embodiment of the method, the inhibitor is selected from the group consisting of an antibody or functional antibody fragment which inhibits LERK-2-mediated cell adhesion (e.g., an anti-LERK-2 antibody), soluble LERK-2 and a LERK-2-Ig chimera. In a particular embodiment, the anti-LERK-2 antibody or fragment is selected from the group consisting of monoclonal antibody 2A1, a functional antibody fragment of 2A1, monoclonal antibody 4A1 and a functional antibody fragment of 4A1.
The invention also relates to a method of detecting or identifying an inhibitor or promoter of LERK-2-mediated cell adhesion, comprising the steps of combining an agent to be tested with a composition comprising a cell expressing LERK-2 and a composition comprising a cell expressing a receptor for LERK-2 under conditions suitable for binding of LERK-2 to a receptor for LERK-2, and detecting or measuring cell adhesion between the cell expressing LERK-2 and the cell expressing a receptor for LERK-2, whereby inhibition or promotion of cell adhesion by the agent is indicative that the agent is an inhibitor or promoter, respectively. The invention also pertains to inhibitors and promoters (i.e., modulators) identified by the described methods.
For example, modulators which can be identified as described herein include modulating antibodies, e.g., antibodies which inhibit or promote LERK-2-mediated cell adhesion. Modulating antibodies can be an antibody or functional antibody fragment which modulates LERK-2-mediated cell adhesion, such as an antibody or fragment which modulates binding of LERK-2 to a receptor for LERK-2. In a particular embodiment, the antibody or functional antibody fragment is an anti-LERK-2 antibody.
In one embodiment the invention relates to an antibody or functional antibody fragment which inhibits LERK-2-mediated cell adhesion, such as an antibody or fragment which inhibits binding of LERK-2 to a receptor for LERK-2. In a particular embodiment, the antibody or functional antibody fragment is an anti-LERK-2 antibody. In a preferred embodiment, the antibody or functional antibody fragment is selected from the group consisting of monoclonal antibody 2A1, monoclonal antibody 4A1, a functional antibody fragment of 2A1 and a functional antibody fragment of 4A1. The invention also relates to an antibody or functional antibody fragment which can compete with monoclonal antibody 2A1 or monoclonal antibody 4A1 for binding to LERK-2 or portion thereof.
The invention also pertains to the hybridoma cell line deposited under ATCC Accession No. HB-12412 and to the hybridoma cell line deposited under ATCC Accession No. HB-12413. The invention further relates to a monoclonal antibody or antigen binding fragment thereof produced by the hybridoma cell line deposited under ATCC Accession No. HB-12412 or HB-12413.
The invention also relates to a method for treating an angiogenic disease, comprising administering to a mammal a therapeutically effective amount of an inhibitor of LERK-2-mediated cell adhesion, whereby angiogenesis is reduced.
The invention further pertains to a method for treating an inflammatory disease or condition, comprising administering to a mammal a therapeutically effective amount of an inhibitor of LERK-2-mediated cell adhesion, whereby inflammation is reduced.
The invention pertains to a method of antitumor therapy, comprising administering to a mammal a therapeutically effective amount of an inhibitor of LERK-2-mediated cell adhesion, whereby angiogenesis is reduced, thereby inhibiting tumor growth.
The invention also relates to a method for enhancing angiogenesis, comprising administering to a mammal a therapeutically effective amount of a promoter of LERK-2-mediated cell adhesion, whereby angiogenesis is enhanced.